Not to be confused with Briones Regional Park, the Briones Reservoir is an East Bay water storage reservoir owned by the East Bay Municipal Utilities District (EBMUD). The lightly traveled trails of East Bay MUD are accessible to hikers with an inexpensive trail permit available online. The Briones Reservoir Loop is a circumnavigation of the entire reservoir that makes a fun trip for experienced hikers. The trails aren't particularly technical or steep, you just need some endurance. The 14-mile trip took us 6 hours flat at a medium/casual pace with two 15-minute breaks. We started at the Bear Creek Staging Area at the corner of Bear Creek and Happy Valley Road. We proceeded clockwise by following the Bear Creek Trail to the Oursan Trail. The first 4 miles is mostly shaded and quite pretty with views of the water. The Oursan trail then wanders surprisingly far from the water and eventually leads you back down the hill along the reservoir for the last few miles. Lots of pollen in the spring, and hot in the summer. Bring lots of water, there isn't any on the hike. We saw an amazing number of birds and butterflies, and had a great time.